Glassman and fellow Republican Commissioner Paul Atkins often clashed with Donaldson over initiatives, including a 2004 rule requiring mutual funds to have an independent chairman, which the agency reaffirmed at a contentious meeting Wednesday.

Donaldson championed the fund rule, adopted last year in a 3-2 vote with support from Commissioners Roel Campos and Harvey Goldschmid, two Democrats whose terms have expired.

Goldschmid is expected to return to teaching at Columbia University Law School later this summer. Campos is seeking a second term at the SEC.

Senate Minority Leader Harry Reid, D-Nev., has recommended that Bush nominate Campos for a second five-year term, and replace Goldschmid with SEC market regulation division director Annette Nazareth. By law, the party that controls the White House may account for no more than three seats on the five-member commission.

Bush announced earlier this month that he intends to nominate Cox to replace Donaldson, but has yet to formally submit the nomination to the Senate for its consideration, and has said nothing about Democratic nominations to the SEC.